Since internally they are still defined as things like GLOWSTONE it will display that even though the cap is changed, should probably see if we're using alternate caps and return that block name instead, the issue here is you can assign multiple blocks to be valid for x tier altar so not sure how you'd pick the right one

Could just use a comma or slash separated list built from the valid blocks for that tier. Or JEI integration that just shows which blocks are valid for caps at each tier.